This invention relates in general to electrical grounding devices and, in particular, to a universal ground clamp for providing an electrical grounding coupling for use with a pipe, conduit or ground rods of various diameters. More specifically, but without restriction to the particular embodiments and/or use which are shown and described for purposes of illustration, this invention relates to a universal ground clamp adapted to accommodate such things as grounding conductors, water service pipes, electrical service conduits, and ground rods having diameters ranging from as small as 1/2" to as large as 31/2".
As is known to those skilled in the art, ground clamps are utilized to provide an electrical ground for pipes and conduits, for example, to dissipate static electricity or whenever it is necessary to protect the safety of persons who might come into contact with such instrumentalities. In effecting such grounding, generally a solid copper wire of preferably AWG sizes 6 through 12 inclusive, is appropriately terminated to ground and then connected to the pipe or conduit by a clamp to effect grounding. However, the coupling of the terminated ground wire to the pipe or conduit to be grounded must be done in a proper manner to ensure an effective electrical connection between the pipe or conduit and the terminated ground wire. This coupling or connection must be maintained at all times free from corrosion and mechanical failure, both at the connection with the terminated ground wire, and at the connection to the rod, pipe or conduit.
While various clamping devices have been utilized to effect such a mechanical and electrical connection, these clamping devices are not generally usable for a wide range of pipe or conduit sizes. Therefore, an inventory of various clamp sizes must be maintained at all times to accommodate these varying sizes, in view of the rather limited range of size accommodation provided by the grounding clamps generally available.
When installing ground clamps, the clamping strap is tightened about the conduit to a predetermined specified torque in an attempt to ensure that the strap is secured to the conduit, but without an excessive force being applied to the clamping strap which might cause strap failure. In the past, prior art clamping devices have utilized a common hexagonally-shaped nut to tighten a clamping strap about the conduit to be grounded which has caused problems by failing to apply the full torquing force to secure the clamp onto the conduit. Since the curvature of the clamping strap passing about the conduit causes the clamping strap to engage the threaded stud at an angle, in such prior art devices the across-points dimension of a hex nut, being greater than the across-flats dimension, many times creates a false torque reading. Such a false reading occurs because of the manner in which the hex nut engages the angled clamping strap, whereby the larger across points dimension permits the edges of the hex nut to engage the clamping strap itself. This contact between the hex nut edge and the strap gouges the strap, and requires an increased force to turn the hex nut on the threaded stud which can erroneously be interpreted as the clamping force between the strap and the conduit. Such prior art devices not only damage the strap, but can fail to sufficiently secure the clamp to the conduit. The present invention protects against such a problem, and permits full utilization of torquing pressure for clamping.
Another problem associated with such prior art is the requirement of the simultaneous use of two tools in order to secure the clamp. In such prior art, when the hexagonal securing nut is tightened, the threaded stud will also rotate unless the stud head is held by the use of a second tool. In the confined spaces where such ground clamps are frequently utilized, the necessity of using two tools simultaneously makes installation difficult. The present invention eliminates the necessity of utilizing two tools in order to secure the clamp on the conduit.